Which of the following statements is true regarding nitrogen oxides hypothesis?

Options:

1. Nitrogen oxides are emitted from the exhausts of large fleet of commercial airplanes.
2. The first commercial flights of supersonic transport aircrafts started in 1986.
3. The impact of nitrogen oxides on stratospheric ozone was first studied by Harold H. Johnston.
4. The Climatic Impact Assessment Programme was launched by the US Department of Transportation to study the impact of sulphate aerosols on ozone depletion.

Correct Answer